Watching “rain” fall

Yesterday was a wet, gloomy day. As we were reading our Highlights Magazine, we found the perfect indoor activity about rain! It took less than 2 minutes to set up and only 5 minutes of our time total, but it gave me a chance to show how evaporation, condensation, and precipitation are related. After we finished, we went for a walk in the drizzle and talked about the water cycle a bit more. The activity didn’t have a huge wow factor, but it was so relevant to the situation and was super simple to set up. 

Rain Demonstration

Step 1: heat water

Step 2: fill a clear cup 1/3 full with warm water

Step 3: cover the cup with plastic wrap and tie it or put a rubber band around it to keep water vapor from escaping

Step 4: put a few ice cubes on top of the plastic wrap

Step 5: watch the “rain” drops form under the plastic wrap and then fall like rain while you talk about evaporation, condensation and precipitation

At the end, when I took the plastic off, all the water that had been condensing on the side of the cup suddenly fell. It looked like rainfall!

What they learned

  • When water gets warm, it starts to evaporate.
  • When small particles of water vapor meet cooler air, they start to gather and form condensation.
  • When enough condensation collects in the “atmosphere” of the cup, it becomes heavy enough to fall as precipitation.
  • Temperature affects the water cycle. 
  • Water has three forms (states): solid ice, gas/vapor and liquid
Water droplets condensing on the side of the cup
Water droplets forming at the top of the cup (our sky or atmosphere)

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